public class BlocksCanvas extends Canvas implements Runnable{ Graphics bg; Image buf; public BlocksCanvas() {  ......  height = getHeight();  width = getWidth();  //按屏幕大小建立缓冲对象  buf = Image.createImage(width, height);  //将缓冲对象的Graphics附给bg  bg = buf.getGraphics();  ...... }     public void run() {......  for(i=0;i<ROWS;i++)  {   for(j=0;j<COLS;j++)   {//画方块    drawBlock(x,y);   }  }  repaint(); } private void drawBlock(int block_x, int block_y) {     //取得方块的坐标  int x = getLeft(block_x);  int y = getTop(block_y);  //取得方块的颜色  int c= board[block_x][block_y];     bg.drawImage(imgs[c], x, y, Graphics.TOP | Graphics.LEFT); } public void paint(Graphics g) {  g.drawImage(buf, 0, 0, Graphics.TOP | Graphics.LEFT); }      }

public class BlocksCanvas extends Canvas implements Runnable{ private boolean stopFlag=false;//调试标志 ...... public void run() {  //断点位置1  testFun(“x:”+x+“y:”+y);  ......  //断点位置2  testFun(“”);  ...... } private void testFun(String str) {    stopFlag=true;  //画一个白色长方形  bg.setGrayScale(255);  bg.fillRect(0,0, fontW, fontH);  //在白色长方形上显示str的内容  bg.setGrayScale(0);  bg.drawString(str, 0,0, Graphics.TOP | Graphics.LEFT);  repaint();  while(stopFlag){} } public void keyPressed(int keyCode) {     stopFlag=false; }       }